With the evolution of wireless communication techniques and protocol standards, mobile packet services have experienced great development, and data throughput of an individual terminal has been increasingly improved. Taking a Long Term Evolution (LTE) system as an example, a bandwidth of 20 M can support data transmission at a maximum downlink rate of 100 Mbps. In an LTE Advanced (LTE-A) system, the data transmission rate is further improved even up to 1 Gbps.
An explosive increase in an amount of data services for a terminal makes existing network resources incapable of meeting demands, which is especially a big problem when new generation communication techniques (for example 3G, LTE) cannot be widely applied to networking, thus it is not possible to meet requirements on rate and traffic desired by a user, thereby resulting in poor user experiences. How to prevent and change this situation is a problem that operators have to consider, on one hand, it is necessary to expedite promotion of new techniques and network deployment; on the other hand, it is desired to accomplish a rapid improvement on network performance through enhancement of existing networks and techniques. It is well known that besides wireless network techniques provided by the 3rd Generation Partnership Project (3GPP), currently used wireless local area networks, especially wireless local area networks based on IEEE 802.11 standards are widely applied to hotspot access coverage in the field of homes, enterprises or even the Internet. Technical specifications proposed by the WiFi Alliance have the widest application.
On the above premise, the present operators have proposed joint transmission based on Wireless Local Area Networks (WLANs) and existing 3GPP networks, i.e., using WLANs to accomplish offload of existing LTE networks and improvement on network performance. At present, the 3GPP has already established relevant protocols for interworking between 3GPP networks and WLANs; as shown in FIG. 1, an existing interworking architecture enables a WLAN network to use an Authentication Authorization Accounting (AAA) server in an LTE network to perform integrated authentication and authorization, and to multiplex a Packet Data Network Gateway (P-GW) in the LTE network to take it as a P-GW of the WLAN, and the existing interworking architecture can also implement integrated accounting and charging of both networks, thereby accomplishing loose coupling between both networks.
However, the current interworking architecture has disadvantages below:
1. the existing interworking architecture depends on the fact that an operator should have an independent 3GPP network and an independent and whole WLAN network, this requires the operator to operate and maintain multiple networks simultaneously, thus leading to higher capital expenditure;
2. a User Equipment (UE) cannot learn whether the network side (e.g., an LTE network and a WLAN network) supports interworking, thus the UE may be connected to a target network that cannot interwork with a current network;
3. switching of data streams is slow when a UE moves between a 3GPP network and a WLAN network; and
4. since existing interworking is triggered by a UE, the network side has no initiative for selecting a target network, thus losing control over a network that the UE accesses, thereby incapable of directing a user to access desired target network or an optimum target network.